1. Technical Field
The present invention relates to elliptical trainers, and more particularly to an elliptical trainer with a variable, track that is adaptable to users with various habitus.
2. Description of Related Art
The conventional elliptical trainer typically has a constant elliptical track to guide a user standing on its pedals to perform reciprocal lower-limb exercise along the constant elliptical track. As the elliptical track is preset, it is impossible for the user to adjust the track according to his/her body height and habitus, rendering his/her exercise rather inconvenient and uncomfortable.
Taiwan Patent No. 472598, for example, provides an adjustable elliptical machine, which comprises a main body lying on the ground. The front and rear ends of the main body are provided with an upright post and a transmission, respectively. The transmission includes a driving wheel. Two links are pivotally connected to two sides of the driving wheel, respectively. The upright post is bilaterally provided with a swinging arm. Each said swinging arm has a lower swinging end that swings to and fro. The swinging end has some a vertical line of equidistant pivotal joints, and the link is pivotally connected to a pedal shaft that is further pivotally connected to the swinging arm. A rail is provided at the middle part of each of the pedal shafts for the corresponding pedal to slide thereon. The pedal is pivotally connected to a rocker arm that is further pivotally connected to the pivotal joint of the swinging arm. Thereby, the driving wheel of the transmission drives the two links to rotate, and each of the link drives the connected end of the pedal shaft to rotate, so that the pedal on the pedal shaft can move along an elliptical track. The elliptical track can be changed by adjusting the stride length of the pedal. Particularly, by changing the site where the rocker arm pivotally connected to the pivotal joint of swinging arm, the elliptical track of the pedal is varied.
However, to perform such an adjustment of the elliptical track in the prior art, the rocker arm has to be first removed from the pivotal joint of the swinging arm, and then reinstalled onto another pivotal joint. In the case that the adjusted stride length is unsuitable to the user, the whole adjusting process has to be repeated, so the known approach to adjusting pedal elliptical tracks is somehow troublesome and inconvenient. In addition, since the transmission is deposited at the rear end of the main body, rendering a rear-driving layout, the range of stride available on the elliptical trainer is limited in view of ergonomic consideration. Particularly, when the elliptical track is of 16″ or more, the pedal, when moving to the front end of the elliptical track, will significantly incline, making the user's ankle rotate toward the user himself/herself. This over-bending motion is not only ergonomically disadvantageous but also dangerous to the ankle joint. For this reason, rear-driving elliptical trainers will be finally overridden by front-driving ones.
Efforts have been made to overcome the shortcomings of the rear-driving elliptical trainers by developing front-driving elliptical trainers. For example, Taiwan Patent No. 499973 provides an improved elliptical trainer, whose main body is pivotally provided with arms rods topped by handles. The arms rod has its lower end pivotally connected to a link that is further pivotally connected to a sliding rod equipped with a pedal. A transmission deposited at the front part of the main body serves to drive a rotating shaft whose end connected to a crank shaft. The crank is pivotally connected to one end of the sliding rod, while an opposite end of the sliding rod is allowed to slide in a guide of a sliding seat on the main body. The prior art device is characterized in that the crank shaft comprises a primary part and a secondary part that are connected by an electric telescopic mechanism therebetween. Thereby, a user can control the crank shaft to adapt the elliptical track to his/her individual body height and habitus.
However, since the telescopic mechanism is attached to the crank, the resulting variation of the elliptical track of the elliptical trainer shows both in the major and minor axes of the elliptical track, causing the elliptical track to be less ergonomically satisfying. Also, the combination of the crank and the telescopic mechanism makes the stride adjustment of the elliptical trainer limited by the volume of the main body.
Hence, it would be desirable to eliminate the shortcomings of the prior art.